Saenuri Party chairman Lee Jung-hyun, one of closest aides to President Park, told reporters that the president expressed her willingness to step down without ending her constitution-guaranteed tenure, according to local media reports.

Lee urged opposition lawmakers to negotiate a roadmap for Park's "honorable retreat," indicating the need for the revised constitution to shorten the single, five-year presidency.

His comments came a day after President Park addressed the nation for the third time since a scandal involving herself and her decades-long friend, Choi Soon-sil, came into focus in October.

The scandal-plagued president threw the ball of decision on her fate in the parliamentary court, saying she will follow the parliamentary decision including the shortening of presidency.

Chung Jin-seok, the ruling party's whip, told reporters that the constitutional revision could become a first step toward reflecting the public wish, proposing the orderly resignation of the president who will stand down in April next year. The presidential election could be held two months later, according to his suggestion.

Three main opposition parties denounced President Park's speech, saying it was a ploy to delay her resignation and impeachment as the shortening of presidency requires the constitutional amendment that would take at least one year or longer.

Heads of the biggest opposition Minjoo Party and minor oppositions People's Party and the Justice Party agreed to continue their push for Park's impeachment as early as this Friday or no later than next Friday when the parliamentary regular session ends.

The impeachment requires at least two-thirds of the 300-seat National Assembly. As there are 172 opposition and independent lawmakers, the impeachment bill must have at least 30 yes votes from the governing party.

The spokesman of anti-Park faction within the Saenuri Party, reportedly composed of 40 to 50 lawmakers, told a press briefing that the constitutional revision for the shortened presidency would not be accepted by the general public.

He said that if rival parties do not agree to any roadmap for Park's resignation, the impeachment should be pursued no later than next Friday.

If the impeachment motion is passed through the parliament, President Park will be suspended immediately, and Prime Minister Hwang Kyo-ahn will become an acting president.